# stptrs.f - Man Page

SRC/stptrs.f

## Synopsis

### Functions/Subroutines

subroutine stptrs (uplo, trans, diag, n, nrhs, ap, b, ldb, info)
STPTRS

## Function/Subroutine Documentation

### subroutine stptrs (character uplo, character trans, character diag, integer n, integer nrhs, real, dimension( * ) ap, real, dimension( ldb, * ) b, integer ldb, integer info)

STPTRS

Purpose:

``` STPTRS solves a triangular system of the form

A * X = B  or  A**T * X = B,

where A is a triangular matrix of order N stored in packed format,
and B is an N-by-NRHS matrix.  A check is made to verify that A is
nonsingular.```
Parameters

UPLO

```          UPLO is CHARACTER*1
= 'U':  A is upper triangular;
= 'L':  A is lower triangular.```

TRANS

```          TRANS is CHARACTER*1
Specifies the form of the system of equations:
= 'N':  A * X = B  (No transpose)
= 'T':  A**T * X = B  (Transpose)
= 'C':  A**H * X = B  (Conjugate transpose = Transpose)```

DIAG

```          DIAG is CHARACTER*1
= 'N':  A is non-unit triangular;
= 'U':  A is unit triangular.```

N

```          N is INTEGER
The order of the matrix A.  N >= 0.```

NRHS

```          NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrix B.  NRHS >= 0.```

AP

```          AP is REAL array, dimension (N*(N+1)/2)
The upper or lower triangular matrix A, packed columnwise in
a linear array.  The j-th column of A is stored in the array
AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n.```

B

```          B is REAL array, dimension (LDB,NRHS)
On entry, the right hand side matrix B.
On exit, if INFO = 0, the solution matrix X.```

LDB

```          LDB is INTEGER
The leading dimension of the array B.  LDB >= max(1,N).```

INFO

```          INFO is INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
> 0:  if INFO = i, the i-th diagonal element of A is zero,
indicating that the matrix is singular and the
solutions X have not been computed.```
Author

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Definition at line 129 of file stptrs.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page stptrs(3) is an alias of stptrs.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK